Foreign Affairs Minister Francois-Philippe Champagne challenged Beijing Thursday over two Canadian planes that left China empty of medical supplies, and pushed for virtual diplomatic access to two Canadians who marked 500 days in Chinese captivity.

“We will continue to defend our interest and principles at every step of the way. With respect to the situation we had with the two planes, it’s a matter of fact. The prime minister spoke about it,” the minister told The Canadian Press.

Champagne was commenting on the remarks a day earlier by the spokesman for China’s foreign ministry, who said it was “inaccurate” for Prime Minister Justin Trudeau to say earlier this week that two Canadian planes left China without the medical supplies that they had been sent to pick up because of congestion at the airport and strict limits on time crews spend on the ground.

Champagne said Canada understands the Shanghai airport is a busy place these days, but he is working with his Chinese counterpart to ensure there are no future empty cargo flights.

At the same time, Canadian authorities have found a million protective facemasks imported from China inadequate for health-care workers. The Public Health Agency of Canada said Thursday that tests found the masks didn’t meet its standards and they won’t be distributed to provinces as planned.

The intense demand for masks means “countries are engaging with a diverse number of new suppliers and manufacturers,” Eric Morrissette wrote in an email.

These masks were billed as meeting “KN95” standard, the Chinese equivalent of the American N95 standard. A PHAC spokesman said the federal government is determining whether they can be put to use outside health settings.

Champagne said he never misses an opportunity in his conversations with Chinese counterparts to advocate for two arbitrarily detained Canadians, Michael Kovrig and Michael Spavor, who are marked their 500th day in Chinese custody Thursday. The two men were arrested in December 2018, nine days after Canada arrested Chinese high-tech scion Meng Wanzhou on a U.S. extradition warrant.

Canada is trying to overcome China’s restrictions on access to prisons during the COVID-19 crisis that have prevented regular consular visits since earlier in the year. China allowed Kovrig to call his ill father last month.

“When I spoke to my Chinese counterpart, I mentioned the concept of virtual consular access and that’s something we’re going to be pursuing, and my understanding is that’s something they are considering,” said Champagne.

“What we’re saying is that in spite of COVID, in spite of conditions that are imposed by local authorities to avoid the spread of the virus in China, that there are means — that there must be technological means today to allow Canada to have consular access for detainees in China, including Michael Kovrig and Michael Spavor.”

Champagne said China is obligated under the Vienna Convention on Consular Relations to allow Canada to check on the well-being of the two men.

“Five hundred days is too much. These Canadians have to be released,” the minister said.

The acting U.S. ambassador to Canada threw the heft of his government behind that demand on Thursday.

“We are aware that today is the 500th day of the captivity for the two Michaels in China. And I just want to reiterate that their return out of this arbitrary detention by the Chinese government remains a priority and a focus for this mission and for the U.S. government and we continue to press the Chinese to prove that they can be responsible members of the international community and take the right steps regarding the two Michaels,” Richard Mills said in Ottawa.